1. Field of the Invention
This invention relates generally to positioning systems, and more particularly, to using wireless communications systems to provide aiding information to a positioning system.
2. Related Art
In densely built urban areas, the use of a positioning system such as a Satellite Positioning System (SPS)—for example, a Global Position System (GPS), also known as NAVSTAR—is often not available or reliable due to various reasons such as, for example, multipath, shadowing, and path loss. In many situations, however, a GPS receiver may be associated with a cell of a cellular communication network and the base station serving that particular cell. Accordingly, one method for mobile phone positioning is to use the cell area coverage information (Cell ID) of the caller as a coarse location estimate to obtain the approximate location of the caller. In urban areas, cell position accuracy may be as close as 100 meters, and therefore the center of a cell can be employed as the alternative position when GPS positioning has a larger error or is not available. The cell ID information is usually or always available and reliable, and is independent of GPS measurements, and can also be easily obtained by paging or updating. Thus, the center of a cell may be employed as an approximate location of a mobile communication device located within that cell.
While the location of the center of a cell may be available to mobile telephone companies, it is usually not available to GPS location providers. Therefore, there is a need for providing systems or methods for making estimated cell center locations available to GPS location providers.